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Part I Surveys of Context-aware Systems. 2008.01.28 임영희. http://idb.korea.ac.kr DB & Mining Lab. Korea University. Contents. Definition of Context & Context-aware Application Architecture of Context-aware System Context Models Existent Context-aware Applications

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part i surveys of context aware systems
Part I

Surveys of Context-aware Systems

2008.01.28

임영희

http://idb.korea.ac.kr

DB & Mining Lab.

Korea University

contents
Contents
  • Definition of Context & Context-aware Application
  • Architecture of Context-aware System
  • Context Models
  • Existent Context-aware Applications
    • Office and Meeting Tools
    • Tourist Guide
    • Memory Aids
    • Context-aware Home
  • Essential Technologies for Context-aware Services
definition of context
Definition of Context
  • Context is
    • situational information
    • any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and application themselves.
    • the set of environmental states and settings that either determines an application’s behavior or in which an application event occurs
categories of context 1
Categories of Context(1)
  • Categories of Context
    • Primary context :
      • Location (where)
      • Identity (who)
      • Time (when)
      • Activity (what)
    • Secondary context
      • can be indexed by primary context
      • Ex) given a person’s identity,

 phone number, addresses, birthdate

given an entity’s location,

 what object are near, what activity is occurring near the entity

categories of context 2
Categories of Context(2)
  • Another categories of Context
    • external (physical) context :
      • can be measured by h/w sensors
      • location, light, sound, movement, touch, temperature…
    • internal (logical) context:
      • be specified by users or captured monitoring the user’s interaction
      • user’s goal, tasks, user’s emotional state…
context aware application
Context-aware Application
  • Definition of Context-Aware
    • A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user’s task
  • Characteristics of Context-Aware application
    • presentation of information and services to a user
    • automaticexecution of a service
    • tagging of context to information for later retrieval
context aware application1
Context-aware Application
  • Categories of Context-Aware applications
    • Active context awareness:
      • An application automatically adapts to discovered context, by changing the application behavior.
    • Passive context awareness:
      • An application presents the new or updated context to an interested user or makes the context persistent for the user to retrieve later
architecture of context aware systems
Architecture of Context-aware Systems
  • Different approaches context-aware systems
    • Direct sensor access:
      • the client s/w gathers the desired information directly form these sensor without layer for gaining and processing sensor data
      • drivers for the sensor are hardwired into the application
      • law extensibility, impossibility of managing multiple concurrent sensor access
    • Middleware based:
      • a layered architecture with the intention of hiding low-level sensing details
      • high extensibility
    • Context Server
      • middleware base architecture + distributed approach
      • gathering sensor data  context server
abstract architecture 1

application

storage/management

preprocessing

raw data retrieval

sensor

Abstract Architecture(1)
  • Sensor
    • sensing hardware + every data source which provide usable context information
  • Categories of Sensor
    • Physical sensors
  • Virtual sensors : sourcing context data from s/w
  • Logical sensors : combining physical sensor + virtual sensor
abstract architecture 2

application

storage/management

preprocessing

raw data retrieval

sensor

Abstract Architecture(2)
  • raw data retrieval
    • raw data retrieval by using appropriate drivers for physical sensor and APIs for virtual and logical sensors
  • preprocessing
    • reasoning and interpreting (transforming)
    • aggregating of raw context data
    • solving of sensing conflicts
abstract architecture 3

application

storage/management

preprocessing

raw data retrieval

sensor

Abstract Architecture(3)
  • storage/management
    • storing context history
  • application
    • implementing actual reaction on different events and context-instances
existent context aware applications
Existent Context-aware Applications
  • Categories of Context-aware Applications
    • Office and Meeting Tools
    • Tourist Guide
    • Memory Aids
    • Context-aware Home
office and meeting tools 1
Office and Meeting Tools(1)
  • The Active Badge System(1992)
    • Group: Olivetti Research Ltd.
    • the first context-aware applications.
    • persons with badges that transmitted IR-signal
    • after sensing a location of a person, forwarding calls to the closest phone
office and meeting tools 2

ParcTab terminal

Office and Meeting Tools(2)
  • The ParcTab System
    • Group: Xerox Palo Alto Research Center
    • ParcTab: small wireless palm-sized computer
    • presenting information about the room the user was in
    • helping the user find the most convenient local resource, e.g. the nearest printer
    • Locating other person with ParcTab  Displaying the location information on Active map
office and meeting tools
Office and Meeting Tools
  • Gaia
    • Group : Dept. of CS, University of Illinois
    • extending typical operating system concepts to include context, location awareness, mobile computing devices and actuators like door locks and light switches
tourist guides
Tourist Guides
  • GUIDE
    • Group: Lancaster University(96~99)
    • terminal: Fujitsu Teampad 7600 portable PC
    • supporting Lancaster city visitor
    • screenshot of GUIDE
memory aids 1
Memory Aids(1)
  • Forget-Me-Not
    • Group: Rank Xerox Research Center
    • PDA system that records where its user is, who they are with, whom they phone, and other autobiographical information and store it in a DB for later query
    • terminal: ParcTab
memory aids 2
Memory Aids(2)
  • StartleCam
    • Group: MIT Media Lab.
    • wearable computer (with digital camera, digital modem) + skin conductivity sensor
context aware homes 1
Context-aware Homes(1)
  • EasyLiving
    • Group: Vision Group at Microsoft Research
    • computer vision for person-tracking and visual user interaction.
    • multiple sensor modalities combined.
    • use of a geometric model of the world to provide context.
    • automatic or semi-automatic sensor calibration and model building.
    • fine-grained events and adaptation of the user interface.
    • device-independent communication and data protocols.
slide20
상황 인식 서비스 요소 기술(1)
  • 상황 인식 서비스 요소기술들
    • 상황정보 감지 기술 (context sensing)
    • 상황정보의 변화 감지 기술(context change sensing)
    • 상황정보 모델링 기술(context modeling)
    • 상황정보 융합 및 추론 기술(context fusion & reasoning)
    • 상황정보 교환 기술(context exchange)
    • 상황정보 툴킷 기술(context toolkit)
    • 상황인식 서비스 묘사 및 발견 기술(context-aware service description language)
    • 상항인식 서비스 구조 기술(context-aware service infrastructure)
slide21
상황인식 서비스 요소 기술(2)
  • 상황정보 감지 기술
    • 상황정보 수집 경로:
      • 사용자 인터페이스, 센서, 센서 네트워크
    • 위치 인식 시스템의 분류
      • 매크로 위치인식 시스템– 광역 위치 인식 시스템(주로 GPS 사용)
      • 마이크로 위치인식 시스템
        • 실내나 지하, 건물 밀집 지역의 위치 인식 제공
        • 적외선 기반, 초음파 기반, 무선랜 기반, 영상 기반 시스템
      • Ad hoc 위치인식 시스템
        • 위치인식을 위한 추가적인 h/w 도입이 어려운 환경에서 사용
        • 위치정보를 가지는 레퍼런스 노드와의 무선 링크 연결성만으로 위치를 계산
slide22
상황인식 서비스 요소 기술(3)
  • 상황정보의 변화 감지기술
    • 상황정보의 변화 주기에 따라 주기적인 polling이나 상황정보가 특정조건을 만족할 경우에만 reporting
  • 상황정보 모델링 기술
  • 상황정보 융합 및 추론 기술
    • 상황정보 융합을 위한 계층적 모델링 요구
    • 지능적인 추론이나 확률적인 메커니즘이 도입
  • 상황정보 교환기술
    • application 간의 복잡한 자료구조를 교환하기 위한 통신 매커니즘 개발이 요구됨
  • 상황정보 툴킷 기술
    • 코딩부담을 줄여주는 비주얼 프로그래밍 툴이 요구됨
slide23
상황인식 서비스 요소 기술(4)
  • 상황인식 서비스 묘사 및 발견 기술
    • 상황인식 서비스 묘사 언어 개발  WSDL등이 사용
    • 서비스 발견 기술  에이전트 기술이 주로 활용
  • 상황인식 서비스 구조 기술
    • 센서, 네트워크, 서비스, 장치 등에 독립적인 infrastructure 개발이 요구됨
part ii context aware artifacts two development approaches
Part IIContext-Aware Artifacts:Two Development Approaches

http://idb.korea.ac.kr

DB & Mining Lab.

Korea University

introduction
Introduction
  • Two development approaches for CA
    • Self-supported context awareness
      • designers build the ability to perceive context, reason with it, and act accordingly into the device or its dedicated hardware support.
    • Infrastructure-supported context awareness
      • designers obtain context aware capabilities by harnessing a hardware and software infrastructure external to and associated with the device’s space.
context aware mobile phones 1
Context-aware mobile phones (1)
  • SenSay
    • context-aware mobile phone that modifies its behavior based on its user's state and surroundings
    • uses a combination of sensors, including a voice microphone, an ambient-noise microphone, accelerometers, and a light sensor.
context aware mobile phones 2
Context-aware mobile phones (2)
  • uses a finite-state machine to track the phone’s internal states (uninterruptible, high activity, normal, and idle)
  • automatically controls ringer and vibration levels, send short-message-service messages to callers, suggest calls to make
  • provides access to the user’s electronic calendar
  • Architecture of Sensay
context aware mobile phones 3
Context-aware mobile phones (3)
  • TEA-II (Technology for Enabling Awareness)
    • self-contained hardware device that plugs into mobile phones to add context-aware capabilities
    • The plug-in’s sensors: two light sensor, two microphones, a dual axis accelerometer, a digital temperature sensor and a touch sensor.
    • detects phone situations( in hand, on table, in pocket, and outdoors)
    • explores an exchange of context information between caller and callee.
    • adds a delay of up to 30 seconds.
    • Doesn’t consider internal phone state and action decision making
other context aware objects 1
Other context-aware objects (1)
  • Sensor-Doll
    • emits different sounds and music according to its situation and how users handle it
  • Spoons and cups
    • Mediacup
    • MIT’s Chameleon Mug
    • MIT’s Intelligent Spoon
other context aware objects 2
Other context-aware objects (2)
  • Funiture
    • Chameleon Table
    • Smart Couch
  • Medication dispensers
    • Context-aware pill bottle
other context aware objects 3
Other context-aware objects (3)
  • Cameras
    • Context photography:
      • uses sound and movement as context information and a set of custom-made computer graphics effects which affect images in real time
      • Example of context pictures
discussion
Discussion
  • Advantages of self-supported CA
    • By equipping objects with sensors, we can gain otherwise unavailable information about the object’s situation
    • Reduced dependency on external infrastructure
  • Challenges of self-supported CA
    • embedding sensors unobtrusively
    • reasoning with the context efficiently and accurately given limited computational resources
    • enabling appropriate actions
infrastructure supported ca 1
Infrastructure-supported CA (1)
  • Infrastructure for CA
    • acts as a mechanism for detecting, combining, and reasoning with different objects’ disparate context information
    • should not only consist of an architecture to represent objects and events, but also provide various services
    • a well-established, pervasive, reliable, and publicly accessible set of technologies that act as a foundation for other systems

The relationship between CA artifacts and the context-awareness infrastructure

infrastructure supported ca 2
Infrastructure-supported CA (2)
  • Weather-aware clothes hanger
    • hangers light up according to the day’s forecast
  • RFID Chef prototype
    • Detects RFID-tagged grocery items on a kitchen counter
    • Display a list of recipes using these items as ingredients
infrastructure supported ca 3
Infrastructure-supported CA (3)
  • Benefits of infrastructure support
    • hardware, platform, and language independence
    • ease of maintenance, in that administrators can change infrastructure-linked services, sensors, and artifacts while the system is running
    • improved context awareness economics
    • Users can update infrastructures and add new artifacts to an existing environment
    • can support complex context-awareness behavior
conclusion
Conclusion
  • Considerations for CA Developers
    • How can a system best acquire context?
    • Should we choose a self-supported or infrastructure-based approach (or some combination)?
    • How can the system reason with and use context for a particular application given the constraints of cost, reasoning efficiency, timeliness of action, and user intelligibility?
    • How can we program such entities to respond appropriately to richer contextual information?
    • How will users perceive automatic responses from artifacts and devices?